Why would they feel this way? “The first-born gets the privilege of [the parents’] undivided attention until the second child is born,” explains Julia Rohrer, a personality psychologist and research fellow with Germany’s Max Planck Institute. “The last-born gets the privilege of undivided attention when the older children have already grown up [and left the house].” Middles, meanwhile, never have the spotlight to themselves.
Some parenting blogs and books argue this imbalance of parental attention leaves middles feeling bitter and resentful, and can lead to later issues with self-esteem or assertiveness.
Does research support the idea of middle child syndrome?
“There is no real support for the idea that middles fare worse in life because of their position among their siblings,” Rohrer says.
Other experts agree. “I think this is one of those things where we have a lot of people in psychology spouting off things that are not supported by systematic data,” says April Bleske-Rechek, PhD, a professor of psychology at the University of Wisconsin-Eau Claire.
“The idea that they’re all messed up by being in the middle is just patently unrealistic,” adds Catherine Salmon, PhD, a professor of psychology at the University of Redlands in California.
How birth order influences your personality
It’s not that birth order doesn’t matter at all. It just doesn’t matter as much, or in the ways most people assume. “There are so many things that influence development and personality,” Salmon explains. While birth order is one of those things, she says a person’s environment, genes, and peer group play their parts. Parental investment and sibling conflict can also have an impact.
Even with all those things in mind, there’s still a lot of ways birth order may impact personality. Here are a few of the most interesting:
First-borns may have higher IQs
“There is one finding that has been replicated multiple times,” Rohrer says. “Firstborn children tend to be a bit smarter on average.” She’s quick to add that, while this IQ difference shows up when researchers examine very large groups of people, it often disappears or flip-flops within individual families—meaning lots and lots of second- and third-borns have higher IQs than their older sibs. Also, the IQ advantage among first-borns tends to be small—the difference between one or two points on an IQ test, Salmon says. “I’m not sure that one or two IQ points make much difference in terms of life outcomes,” she adds.
Later-borns may be more rebellious
There is some research that suggests later-born children are more rebellious than their first-born sibs, Salmon says. In this context, “rebellious” means branching out from their parents’ lifestyles. So while first-borns may follow in their parents’ footsteps, later-borns—seeking to differentiate themselves—may be more likely to choose different paths, research suggests.
“There is some evidence that later-borns are more willing to take risks,” Salmon says. But she says there’s not much research specifically on middle children compared with later-born children. And again, the effect here (if it exists) is small and highly variable from person to person.
Middle-borns may be better negotiators
“I think that one of the benefits of growing up in a family with lots of children is that, if you’re in the middle, you have to negotiate a lot to get what you want,” Salmon says. The oldest child is often bigger and can just take what they want, the youngest can use the whiny baby strategy to influence their parents, while middles often have to develop good negotiation tactics and people skills to get what they want, which could benefit them outside the home, she says.
Middle-borns may lean on their siblings and friends, not their parents
While first-borns and last-borns may be more likely to reach out to their parents when dealing with hardships, middle-borns may instead look first to their siblings and friends for support, finds one of Salmon’s studies. “Middle-borns tend to be quite attached to [their] friends,” she says. Depending on the type of “peer group” a middle child has, this could be either a good or bad thing. “You could see how this could lead to some problems, and there are some studies that show higher rates of delinquency among seconds,” she says.
First-borns may be more conscientious
One 2007 study in Evolution & Human Behavior found first-borns may be more likely to be “conscientious” than their younger sibs. In this study, conscientiousness meant being responsible and organized. Salmon says this and other research efforts suggests first-borns may be more “conservative” than later-borns in the sense that they follow the rules and place emphasis on performing well in school and in other “traditional” spheres. But, again, the effect here is likely to be small.
Later-borns may be more open-minded
The same 2007 study found that later-borns may be more open-minded and willing to explore new experiences. The study defines openness as tending toward “unconventional” or “liberal” attitudes. “Later-borns may be more prone to fantasy, or more open—not gullible, but more willing—to believe things,” Salmon says.
Birth order effects may be more apparent when all siblings are the same gender
“If you look at larger families where all the kids are the same gender, birth order things seem to be more pronounced,” Salmon says. She says the parental resource allocations that may lead to some small birth order effects in all-boy or all-girl families often disappear in boy-girl-boy or girl-boy-girl sibling groups. She also says birth order effects seem to be a lot more pronounced within families than outside of them. (While you may be the bashful one in your super-extroverted family, for example, you may not be shy at all when compared to the average person.)
First-borns may feel more parental pressure to achieve
“You look at first-borns, and I think often a lot of expectations are put on them,” Salmon says. The oldest siblings may have to live up to their parents’ “lofty goals and ideals,” she says, while later-borns may feel more free to make their own decisions. “I think that independence gives [some later-borns] the ability to explore different things and what’s going to be best for them,” she says. One recent study found later-borns may be more likely than firsts to enter creative occupations like architecture, music, or writing, while first-borns are more likely to go into business or law.
Later-borns may have better mental health
Later-born children may have a mental health advantage over their older sibs, shows a 2010 study from Social Science & Medicine. “The presence of older siblings was associated with relatively good mental health, while the presence of younger siblings was associated with relatively poor mental health,” the authors of that study say. Additionally, kids with older brothers and sisters tended to score better on measures of hyperactivity and emotional health, the study data show.
This article originally appeared on Prevention US.